Is it normal for my grandma to like giving me a footjob

my grandma came over from barbados in the summer to look after me, when she arrived at my house she was wearing open toed high healed shoes, i ran down stairs to come see her i was in my under pants, as soon as i looked at her feet i got a boner and my penis came out of my pants i was scared, after my parents left to get shopping my grandma went to sleep cause of jetlag i followed, i was sitting at the edge of the bed looking at her toes, then she told me to suck her toes next thing i no is pulling down my boxer i had the biggest boner afer she was mastrabing me with her feet then she stripped the cum sprayed into her mouth and said dont tell mom